The thick-billed grasswren (''Amytornis modestus'') is a species of

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

in the family

Maluridae The Australasian wrens are a family, Maluridae, of small, insectivorous passerine birds endemic to Australia and New Guinea. While commonly known as wrens, they are unrelated to the true wrens. The family comprises 32 species (including sixteen ...

. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to Australia. Its natural

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

is Mediterranean-type shrubby vegetation.

Taxonomy and systematics

The thick-billed grasswren was formerly considered as

conspecific Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organis ...

with the western grasswren until split as a separate species in 2010.

Subspecies

Seven subspecies have been identified in recent studies (Black 2011, 2016; Austin et al. 2013): * †''A. m. modestus'' – (

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography. Etymology The word ''north ...

, 1902): Now extinct. Formerly found in Northern Territory * ''A. m. indulkanna'' – ( Mathews, 1916): Found in

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an Australian territory in the central and central northern regions of Australia. The Northern Territory shares its borders with Western Aust ...

and

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

* ''A. m. raglessi'' – Black, 2011: Found in

Flinders Ranges The Flinders Ranges are the largest mountain range in South Australia, which starts about north of Adelaide. The ranges stretch for over from Port Pirie to Lake Callabonna. The Adnyamathanha people are the Aboriginal group who have inhabit ...

in South Australia * ''A. m. curnamona'' – Black, 2011: Found in Lake Frome Basin in South Australia * ''A. m. cowarie'' – Black, 2016: Found in Sturt Stony Desert in South Australia * ''A. m. obscurior'' – (Mathews, 1923): Found in

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

* †''A. m. inexpectatus'' – (Mathews, 1912): Now extinct; formerly found in

Description

The thick-billed grasswren has dull brown underparts, a long dark-brown tail and noticeable white streaking on the head. It has white streaks continuing down the neck, throat and down to the rump. The white streaks across the chin to the forehead and along the wings and rump, contrast with the red-brown to grey colours of the feathers. Males have distinguishably longer tails. Females also have chestnut flanks. Vocals are a combination of short high-pitched song, repeated. They have a soft, high-pitched call that is often inaudible to human ears.

Distribution and habitat

The thick-billed grasswren is endemic to Australia and is found throughout the arid regions of northwestern New South Wales, northern parts of South Australia, through to southern sections of the Northern Territory. It is also speculated to still occur in fragmented populations in the Grey Range of

Sturt National Park The Sturt National Park is a protected national park that is located in the arid far north-western corner of New South Wales, in eastern Australia. The national park is situated approximately northwest of Sydney and the nearest town is , awa ...

. Chenopod scrublands (consisting largely of

saltbush Saltbush is a vernacular plant name that most often refers to '' Atriplex'', a genus of about 250 plants distributed worldwide from subtropical to subarctic regions. ''Atriplex'' species are native to Australia, North and South America, and Eurasia. ...

), sandhill cane-grass and flood debris in dry, sandy watercourses. They favour the scrublands with dense chenopod bushes. These denser shrublands usually occur in lower-lying areas, such as watercourses and drainage lines.

Behaviour and ecology

Thick-billed grasswrens are usually sedentary, with these elusive birds seen running, hopping or rarely flying, between vegetative cover to remain undetected. They can also be seen foraging for food at ground level around vegetation. Wrens have a generalist beak type that allows them to eat a range of foods. The thick bill allows for tougher seeds and other food niches to be accessed, compared with the smaller fairy wren species. If disturbed, individuals take refuge in any existing cover – usually vegetation or piles of old flood debris along dry sandy watercourses and even down rabbit burrows. They are often seen solitarily or in pairs. Sources vary, but mating pairs maintain between five, and 20 to 40 hectare territories year-round and rarely, possibly never, band with their neighbours outside the breeding season. Family groups are sometimes seen during the post-fledgling period, while the young are still dependent on their parents. The feather patterns/markings imitate their preferred habitat as a form of camouflage.

Breeding

Breeding occurs between July and September. Nests can usually be seen in low branches in saltbush, can-grass and other similar vegetation. The nest composes of loose grass and bark in the shape of a half dome, with finer grass, fur, feathers lining the nest. One to three (usually two) eggs of various colourings of white, cream and pink; with blotches of red-brown or purplish grey. They have an incubation period of two weeks and fledge in 10–12 days. The estimated generation length of the thick-billed grasswren is four years .

Feeding

The thick-billed grasswren eats mainly insects and other small

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s, as well as plant seeds and berries.

Conservation status

The main threat to thick-billed grasswrens is loss of habitat through clearing and

overgrazing Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature res ...

by hard-hooved animals, such as sheep and goats that trample the vegetation. This reduces the area and quality of the habitat that the thick-billed grasswren prefer, particularly the larger shrubs that provide prime habitat for breeding. Habitat modification has also occurred due to rabbits.

Feral A feral () animal or plant is one that lives in the wild but is descended from domesticated individuals. As with an introduced species, the introduction of feral animals or plants to non-native regions may disrupt ecosystems and has, in some ...

species, such as

foxes Foxes are small to medium-sized, omnivorous mammals belonging to several genera of the family Canidae. They have a flattened skull, upright, triangular ears, a pointed, slightly upturned snout, and a long bushy tail (or ''brush''). Twelve sp ...

and cats are major threats due to predation. High-frequency

bushire Bushehr, Booshehr or Bushire ( fa, بوشهر ; also romanised as ''Būshehr'', ''Bouchehr'', ''Buschir'' and ''Busehr''), also known as Bandar Bushehr ( fa, ; also romanised as ''Bandar Būshehr'' and ''Bandar-e Būshehr''), previously Antioc ...

s are also a threat to the quality of habitat. Higher frequency of fires disrupts the life-cycle processes of the thick-billed grasswren, as well as the plants and

macroinvertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s that they depend on. All threats have been compounded by droughts over the past decade. Changes in expected environmental conditions will also challenge tolerance ranges and exacerbate the impacts of existing threats to the species. The thick-billed grasswren is a poor flyer, and because of this has a poor dispersal capability and is highly susceptible to

population fragmentation Population fragmentation is a form of population segregation. It is often caused by habitat fragmentation. Causes of Fragmentation Fragmentation can be the cause of natural forces or human actions, although in modern times, human activity is th ...

. The thick-billed grasswren was listed as a

vulnerable species A vulnerable species is a species which has been categorized by the International Union for Conservation of Nature as being threatened with extinction unless the circumstances that are threatening its survival and reproduction improve. Vulnera ...

under the Commonwealth ''

Environment Protection and Biodiversity Conservation Act 1999 The ''Environment Protection and Biodiversity Conservation Act 1999'' (Cth) is an Act of the Parliament of Australia that provides a framework for protection of the Australian environment, including its biodiversity and its natural and cult ...

'' (EPBC Act) on 26 July 2000, and as critically endangered under the ''

Biodiversity Conservation Act 2016 (NSW) The ''Biodiversity Conservation Act 2016'' (''BC Act'') is a state-based act of parliament in New South Wales (NSW). Its long title is ''An Act relating to the conservation of biodiversity; and to repeal the Threatened Species Conservation Ac ...

'' (February 2022 list) in New South Wales. However the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

(2021.3 list) accords it a status of "least concern", . The subspecies ''Amytornis modestus obscurior'' (north-west NSW) is listed as critically endangered by both the New South Wales and

Commonwealth Government The Australian Government, also known as the Commonwealth Government, is the national government of Australia, a federal parliamentary constitutional monarchy. Like other Westminster-style systems of government, the Australian Government ...

s. A 2018 study ranked the species eighth in a list of Australian birds most likely to go extinct.PDF
/ref>

References

Barrett, G.W., Silcocks, A.F., Cunningham, R., Oliver, D.L., Weston, M.A. & Baker, J. (2007). Comparison of atlas data to determine the conservation status of bird species in New South Wales, with an emphasis on woodland-dependent species. ''Australian Zoologist'', 34, 37–77. Cayley, N. W., Chisholm, A. H., Hindwood, K., McGill, A. R., Roberts, P., & Lindsey, T. (1991). ''What bird is that?'' Angus & Robertson: Australia. Garnett, S. & Crowley, G. (Eds) (2000). ‘The Action Plan for Australian Birds 2000’. (Environment Australia: Canberra). Government of South Australia, South Australian Arid Lands Natural Resource Management Board (2011). Fact sheet: thick-billed grasswrens. Retrieved from www.saalnrm.sa.gov.au Higgins, P.J., Peter, J.M. & Steele WK (Eds) (2001). ''Handbook of Australian, New Zealand and Antarctic Birds'', vol. 5. (Oxford University Press: Melbourne). McAllan, IAW (1987). Early records of the Thick-billed Grasswren Amytornis textilis and Striated Grasswren Amytornis striatus. Australian Birds 21, 33–34. McAllan, IAW (2000). On some New South Wales records of the Grey Grasswren and the Thickbilled Grasswren. ''Australian Bird Watcher'', 18, 244–246. NPWS (2002). Thick-billed Grasswren (eastern subspecies) Amytornis textilis modestus (North, 1902) Recovery Plan. NSW National Parks and Wildlife Service, Hurstville NSW. Pizzey, G., & Knight, F. (2012). ''The field guide to the birds of Australia''. Harper Collins Publishers: Australia. {{Taxonbar, from=Q12253402

thick-billed grasswren The thick-billed grasswren (''Amytornis modestus'') is a species of bird in the family Maluridae. It is endemic to Australia. Its natural habitat is Mediterranean-type shrubby vegetation. Taxonomy and systematics The thick-billed grasswren wa ...

Birds of the Northern Territory Birds of South Australia Birds of New South Wales Endemic birds of Australia

Taxonomy articles created by Polbot